We’ve blogged about fish passage here in the Yakima Basin before – about how the reservoirs that power our agricultural economy were constructed without passage systems, and the steps the Yakima Plan partners have taken to restore struggling and extirpated species. Almost a year later, we’ve moved a lot of ground on construction of the $100 million downstream passage facility at Cle Elum Reservoir, but what about upstream passage? What about the sockeye returning to spawn in the lake?
Cle Elum Dam poses some unique challenges on that front. At 165-feet high, the dam is too tall and steep to accommodate a traditional fish ladder. The reservoir itself rises and falls throughout the year as the water is tapped for irrigation, another mark against typical ladder systems. The original downstream passage designs incorporated a trap-and-haul facility below the dam, where returning adults would be gathered, moved to a tanker truck, and driven up to the lake.
One new alternative could let the fish move themselves. It’s called the Whooshh, and its engineers have been working with Yakama Nation Fisheries biologists at Roza Dam all summer, conducting tests to determine its impacts on the health, mortality rates, egg viability and fecundity of spawning salmon. The Whooshh is a flexible pressurized tube, similar to the type used at drive-up bank windows, capable of transporting fish at speeds of 25 feet per second. Cle Elum will require a 1100-foot long tube, the largest ever designed by Whooshh Innovations, to span the height of the dam, the length of the spillway, and the seasonal drawdown of the reservoir.
Fish moved via Whooshh expend no energy compared to fish tackling traditional ladders, leaving them with more stored nutrients to put toward egg development. The Roza Dam trials will help biologists gauge whether the stress of being removed from the water and sped through a tube is more, less or comparable to trap-and-haul techniques. Until all the numbers are crunched, this is just one possible alternative, but these tests continue to demonstrate the Yakima Plan’s commitment to innovation and best practices!
For more footage of the Roza trials, check out KNDO 23’s piece, or the Department of Ecology’s video.